Dying Power Amp?

Discussion in 'AV Receivers' started by Matt Lee, May 4, 2004.

  1. Matt Lee

    Matt Lee Agent

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    Hi, posted about this awhile ago but didn't get any response so I thought I'd try again as the lacking audio performance in my HT is starting to get to me.

    My roommate is running a Panasonic SA-HE100 through my JBL S38IIs and S-Center in the front and a pair of HIS Bose (I know, I feel dirty) 201s in the rear (I'm going to be replacing them with S26IIs soon). The first few months in our new apartment we had great results but lately we have two symptoms.

    1) The surround channels occasionally cut out. Its not the wiring or the speakers because they both cut out at the same time when it happens. Sometimes they kind of flicker in and out a bit too. We've checked and double checked that we were in the right sound modes.

    2) In general the sound seems a bit dull and lacks punch. This is a very subjective assessment, but when we moved in it seemed a lot more dynamic and well, just better.

    Any thoughts? My only guess is that something is wrong with the power section or part of it. His warranty is up, but he's planning on calling Panasonic anyway (though its taking forever to get him to do so).

    I can't wait until I save up enough to replace it with an H/K. (probably 525 or 430)
     
  2. John Garcia

    John Garcia Executive Producer

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    Does it do it at any volume, or only when turned up? Doesn't sound like it is dying, sounds like it is being overdriven. IMO, the JBLs up front will pull a lot of current for that receiver. If it doesn't do the same thing at the same volume in stereo, then the receiver cannot provide enough current for the SPL you are asking of it with those speakers.
     
  3. Matt Lee

    Matt Lee Agent

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    I've only really noticed it when watching movies, but I haven't noticed it happening more at any particular volume. Sometimes we put something on and the surrounds are working, sometimes they're not, sometimes you can hear them going in and out. What you suggest might make sense, except that this is a more recent phenomenon and if the JBLs drew too much current (which I don't entirely understand, they're 8ohm speakers with 89db sensitivity, if anything the Bose are 4ohms I think) wouldn't this have been happening all along?
     
  4. JimMAC

    JimMAC Agent

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    Since you only notice it during movies, it is a normal feature of movies that the surrounds are not always used. They will cut out but not dramatically, depends a lot on what the director wanted you to hear. Try running a cd through all channels with a digital processing setting on the amp. If it does not cut out there, I would expect it may be the movies your watching.

    Mac
    PS just purchased the HK 430, go for it. [​IMG]
     
  5. Matt Lee

    Matt Lee Agent

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    Sorry, I guess what I said was misleading. I have noticed it on other sources, including music DVDs, it is definitely not just an intended mixing thing. Its just a little more obvious on 5.1 theatrical stuff vs say TV with DPL running, 'cause sometimes the surrounds are extremely subtle with that.

    The first time we noticed it we put on a 5.1 music DVD and heard nothing from the surrounds, we assumed we had the wrong mode on but checked and it was fine. We assumed it was the 5.1 mix (ie: a really crappy one w/no surrounds) but the next day it worked just fine in 5.1

    As for the 430, I'd like to go with that, but I find it hard to justify spending more when I can get a refurb 525 for like $450 (haven't seen 430s under $600) which is at least rated at slightly more power. Its a tough call but since both have the same number of channels and similar power, I'll probably go with the 525 to save cash. I also did an A/B of the 525 vs the 430 (or maybe it was 630, I forget) at Circuit City and found the different in actual sound to be almost indistinguishable, and whatever the difference was, I couldn't pick one as sounding "better" so I'm sure I'll be thrilled with whichever I get.
     
  6. John Garcia

    John Garcia Executive Producer

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    89db sensitivity is actually somewhat low. Not out of the question, but this is a ~$200 receiver and I can pretty much guarantee you it is going to struggle with those speakers. The risk you are running is damaging the speakers.

    Try disconnecting the main speakers and run just the rears. If the same thing happens, the receiver is likely the problem or possibly even the DVD player. Does it happen in digital only or in analog as well?
     
  7. Matt Lee

    Matt Lee Agent

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    I was a little concerned about the receiver at first, but S&V said it put out a solid 70watts/ch vs its 100 rating, so I figured it couldn't be too bad.

    Anyway, there was another issue that I basically ignored earlier on (we've been running this setup since last september) which was that at the time, certain sounds, I don't know if it was at certain frequencies ('cause it seemed to happen at very moderate volumes as well as running stuff loud) mostly on dialogue, peoples voices seemed to kind of flatten out, especially when people were yelling. I figured it was a problem with the receiver handling it, but didn't know if it was necessarily clipping or not (since I'd more often heard that described as either pops/clicks or completely inaudible distortion). Anyway, I ignored it 'cause there wasn't much I could do about it at the time (coudln't afford my HK receiver yet). Now that's stopped but instead we have this surround problem and more importantly, everything just sounds a little more dull and lifeless than it used to, less punchy.

    The thing that seems weird is if its simply the receiver not being able to handle the speakers, why it wasn't like this from the beginning? When we first set this all up I thought even up to -26 was pretty loud to me (-11 was reference, calibrated with DVE), but now I seem to have to turn it up to -20 just to get a decent movie watching volume.

    So the only conclusion I can draw is something has been damaged since then. I was hoping it was the receiver just giving out but now I'm afraid it might be my speakers.

    Do you think there's a good chance I've already damaged my speakers? They don't seem to pop/click much, which I heard what a big symptom of that, but I don't really know much about it. Or is there still a good chance they'll sound fine when I put a more powerful receiver in there?

    Also, if this is the case, would you recommend I wait on getting my S26II surrounds, since those are 87db sensitivity, until I get my receiver?

    Thanks for all the responses, I appreciate the help. I only wish I could disconnect my speakers until I get my new receiver. But my roommates would think I'd lost it (I've already been Mr. Anal HT Guy since I got a CRT RPTV, burn-in paranoia and all that).

    PS. I've only noticed it in digital but we don't really run any analog sources through the receiver so I can't say. But it does happen on both 5.1 and stereo sources (w/DPL processing).
     

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